Non-destructive mechanical characterisation of thin-walled GFRP beams through dynamic testing and model updating

This work deals with a non-destructive approach based on dynamic testing combined with model updating techniques through finite element modelling and optimisation processes to characterise the main elastic constants of a thin-walled glass fibre reinforced polymer (GFRP) C-channel beam. The experimental modal analysis identified nine vibration modes encompassing global modes predominated by coupled flexural-torsional behaviour as well as local flexural ones related to the flanges of the beam. The longitudinal elasticity and in-plane shear moduli were less sensitive to the number of modes, indicating that only the first three modes were enough to obtain a good estimate of these parameters. In contrast, the transverse modulus of elasticity was more affected over the nine modes and the optimisation process became imperative to seek the optimal value. As corroborated by destructive tests, the non-destructive procedure gives an alternative approach for the mechanical characterisation of GFRP members, which can be advantageous for low-cost in situ quality control. •Dynamic characterisation of a thin-walled GFRP C-channel beam targeting low-cost in situ quality control of GFRP beams.•Identification of nine vibration modes, including both global coupled flexural-torsional behaviour and local flexural ones.•The influence of the model updating on the material elastic constants was corroborated by destructive tests.•The first three modes were enough to obtain a good estimate of the longitudinal elasticity and in-plane shear moduli.•The transverse modulus was more affected over the nine modes; the optimisation became imperative to seek its optimal value.